By IRVIN MOLOTSKY

Published: February 17, 1984

Mr. Stone, who could not be reached by telephone for comment tonight, was sworn in as the special envoy last June 1. He has made many trips to Central America, particularly to El Salvador, to reassure that nation about United States support.

Mr. Stone was said to have resigned not because of any policy differences between him and the Administration but rather because of personality clashes with Langhorne A. Motley, the Assistant Secretary of State for Inter- American Affairs.

Mr. Motley often referred to Mr. Stone in caustic terms in private conversations with journalists, and the two men are known not to have got along. Likely to Remain

An Administration source said that Mr. Stone, a conservative Democrat and former United States Senator from Florida, would probably remain in the Administration in another capacity.

A White House spokesman declined to confirm that Mr. Stone had resigned, saying only, ''Ambassador Stone is a valued member of our diplomatic effort and we have no changes to announce at this time.''

Early in his tenure, Mr. Stone made several well-publicized trips to Central America, seeking to help initiate discussions between the Salvadoran Government and anti-Government forces, and discussions between the Administration and the Sandinista leaders in Nicaragua.

With the Colombian President, Belisario Betancur, acting as an intermediary, Mr. Stone held several discussions with Salvadoran guerrilla leaders in Colombia but never made much progress in getting the two sides to talk.

Recently those efforts had been set back by the apparent decision by Salvadoran authorities to hold off on such talks until after their presidential election. Liaison With Contadora Group

Mr. Stone said recently that he felt progress was possible in discussions between the United States and Nicaragua, and had met several times in recent months with Nicaraguan leaders.

He has also been the Administration's main liaison with the four Latin American nations that have been attempting to develop a regional peace plan. Those nations - Venezuela, Colombia, Panama and Mexico - are referred to as the Contadora Group, after the Panamanian island where they first met in 1982.

While Mr. Stone was traveling back and forth, opponents of Administration policies in Congress suggested that his mission was a means of diverting attention from increasing United States military involvement in the region. Mr. Stone said his efforts reflected a serious interest by the Administration in finding diplomatic solutions.